CVE-2025-63419 is a Cross Site Scripting (XSS) vulnerability identified in CrushFTP version 11.3.6_48, a popular web-based file transfer server. The vulnerability stems from the file sharing feature, where the filename is reflected directly into an email body field without any sanitization or encoding. This lack of input validation allows an attacker to inject arbitrary HTML or JavaScript code into the email content, which is then rendered in the recipient's browser when they view the email. The attack vector involves crafting a malicious filename that includes script code; when the server inserts this filename into the email body, the script executes in the context of the user's browser session. This can lead to various malicious outcomes such as stealing session cookies, redirecting users to phishing sites, or performing actions on behalf of the user. The vulnerability does not require prior authentication, increasing its risk profile, but does require the victim to interact with the malicious email content. There are no known public exploits or patches available at the time of publication, and the CVSS score has not been assigned. The flaw primarily affects confidentiality and integrity by enabling unauthorized script execution and potential data theft. The scope is limited to users receiving shared file emails from vulnerable CrushFTP servers. The vulnerability highlights the importance of proper input validation and output encoding in web applications, especially those handling user-generated content in email communications.

For European organizations, the impact of CVE-2025-63419 can be significant, particularly for those relying on CrushFTP for secure file sharing and transfer. Exploitation could lead to unauthorized access to sensitive information, including credentials and session tokens, potentially compromising internal systems and data confidentiality. This is especially critical for sectors like finance, healthcare, and government, where data protection regulations such as GDPR impose strict requirements on data security and breach notification. The vulnerability could also facilitate phishing campaigns by injecting malicious content into legitimate file sharing emails, increasing the risk of social engineering attacks. Additionally, compromised user sessions could allow attackers to perform unauthorized actions, impacting system integrity and availability. Although no active exploits are reported, the lack of a patch means organizations remain exposed until mitigations are applied. The reputational damage and regulatory penalties following a breach could be severe, making timely remediation essential.

To mitigate CVE-2025-63419, organizations should implement the following specific measures: 1) Immediately review and restrict the use of CrushFTP version 11.3.6_48, considering temporary suspension of the file sharing feature if feasible. 2) Apply strict input validation and output encoding on all user-supplied data, especially filenames reflected in email bodies, to neutralize HTML and script content. 3) Employ web application firewalls (WAFs) with custom rules to detect and block suspicious payloads in HTTP requests related to file sharing. 4) Educate users to be cautious with file sharing emails and to report suspicious content. 5) Monitor email systems for unusual patterns that may indicate exploitation attempts. 6) Engage with CrushFTP vendors or community to obtain patches or updates addressing this vulnerability. 7) Implement Content Security Policy (CSP) headers to restrict script execution in browsers where possible. 8) Conduct regular security assessments and penetration testing focused on web application input handling. These steps go beyond generic advice by focusing on the specific vector of reflected filenames in emails and the operational context of CrushFTP deployments.